The use of brackets is widely known as orthodontic treatment for malocclusion. Dental arch is corrected by attaching brackets and the like to teeth and applying physical tension, namely a restoring force, such as a pushing force, a pulling-back force or a torsion force, of an archwire attached to these brackets, to the teeth to gradually change the positions of the teeth.
For normal use, a groove is formed in the bracket for causing an archwire to slide or be fixed in the center of the bracket body and the archwire is held in the groove by various ligating means. In the case of emphasizing aesthetic appearance in particular, plastics or ceramics have recently come to be used as materials of such brackets in addition to conventional metal. On the other hand, titanium alloy, stainless steel or other non-rusting materials are used for the material of archwire.
Various modifications of such orthodontic brackets are known. However, though these brackets are made of plastic, they have a groove (slot) and the archwire is held in a constrained state in the groove. Examples of ligating means for archwire include that which holds the archwire by means of wings provided on the outside of the brackets and that of the same configuration which composes a locking member holding the archwire by way of elastic deformation. Moreover, another known example of ligating means is that which employs a configuration holding the archwire by pressing the ligating means onto the brackets from above.
As seen from detailed description of the prior art, an orthodontic bracket is disclosed which is composed so as to hook and hold the archwire with a bent, L-shaped locking member that is made of an elastic plate and has one portion rotatably engaged by a tab formed on the lower portion of a wing as well as has a hooking portion formed at its upper end. (see, for example, Japanese Patent Application Laid-open No. 2007-202: Patent Document 1).
In addition, a bracket is also disclosed that employs a configuration in which guide grooves are provided in wings, the outer walls of the wings are formed roughly in X-shape and, after inserting the archwire into the guide grooves, the archwire is caused to fit into and attached to the X-shaped grooves with a ligature wire or rubber band (see, for example, Japanese Utility Model Laid-open Publication No. H5-63517: Patent Document 2). Moreover, a bracket is disclosed in which a wire is removably ligated by elastically deforming synthetic resin ligating member and causing it to fit into a wire insertion groove formed on a bracket from above (see, for example, Japanese Patent Application Laid-open No. 2004-329912: Patent Document 3). Although the hooking portions are wings in this method as well, this configuration allows the wire to be attached from above the bracket in a single operation.
As was previously described, treatment for correcting dental arch by using an archwire involves repositioning of the teeth while applying force thereto. The archwire is held by brackets with wings using ligating members such as ligature wires or rubber bands. Conventional methods involved pressing the archwire onto the bracket with a pressing force exceeding necessary extent.
In addition, the pushing force on the archwire can be reduced in order to reduce the strength of force applied to teeth. In the case of a conventional ligating method using a ligature wire with wings or a ligating method that uses rubber bands through elastic deformation, pressing force exceeding necessary extent is inevitably applied and attachment and removal of the archwire requires a complex procedure. In addition, conventional ligating members have a complex, involute configuration in which there are numerous irregularities in relation to the bracket.
Consequently, the structure of conventional brackets makes food particle, plaque and other foreign substances apt to remain on them, which is unsanitary. In addition, these brackets also lacked aesthetic qualities. There are many examples of orthodontic treatment using these brackets that employ means for ligating the archwire through wings on the bracket. However, a method in which a ligating member fits into wings from above the bracket to ligate the archwire in a groove in the bracket is a type of self-ligating method and the pressing force by the wire decreases due to the formation of gaps between the ligating member and wire.
Although this method facilitates the initial attachment procedure, the archwire must be repeatedly re-ligated during the course of orthodontic treatment and there is also a problem of the procedure requiring considerable complexity for the orthodontist in operation of attaching and detaching of the archwire. In addition, this composition requires the ligating member to be detached during removal and, due to the extremely small size of the ligating member, there is a risk for the ligating member to fall off. Moreover, since the wings have a protruding portion and the like, there is a problem where aesthetic characteristics are impaired from a Viewpoint of aesthetic appearance.
Another known example of self-ligating is of a type in which a bracket and a ligating member are integrally composed. Namely, a type is known in which an archwire is held by covering the open side of a slot with a shutter (see, for example, Japanese Patent Application Laid-open No. 2005-58742: Patent Document 4 and Japanese Patent Application Laid-open No. 2006-192272: Patent Document 5). In addition, a type is also known in which an archwire is held by covering it with a rotating locking member (see, for example, Japanese Patent Application Laid-open No. 2001-104340: Patent Document 6). Moreover, a type is also known in which an archwire is held by inserting it into a latch (see, for example, Japanese Translation of PCT Application No. 2003-510128 (WO 01/022901): Patent Document 7 and Japanese Translation of PCT Application No. 2006-505327 (WO 2004/041109): Patent Document 8). Although these integrated configurations facilitate the ligation and release procedures, they are all of the self-ligating types, hence they have irregularities with respect to their structure, thereby resulting in the shortcomings of inferior aesthetic properties and cleanability.
In these types of brackets in the prior art, the configurations thereof are not satisfactory in terms of providing orthodontic treatment. Thus, there is a need for a bracket that overcomes the problems of these conventional configurations, reduces the degree of irritation of mucous membranes for the patient, exhibits superior sanitary properties and facilitates the ligation procedure for the orthodontist. In addition, there is also a need for a bracket with which such a superior orthodontic technique is effectuated that facilitates wire control while also enabling a ligation technique with improved aesthetic appearance to be exhibited.